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991.
Jian-Po Zhang Xin Zhou Fu-Quan Bai Hong-Xing Zhang Au-Chin Tang 《Theoretical chemistry accounts》2009,122(1-2):31-42
The geometries, electronic structures, and spectroscopic properties of a series of [Os(II)(CO)3(tfa)(acac(X)2)] (tfa = trifluoroacetate; acac = acetoylacetonate; X = H (1), CF3 (2), C6H5 (3), and C10H7 (4)) complexes have been investigated theoretically. The ground and excited state geometries were optimized at the B3LYP/LANL2DZ and CIS/LANL2DZ levels, respectively. The optimized geometry structural parameters agreed well with the corresponding experimental results. As indicated in this paper, the highest occupied molecular orbitals were dominantly localized on the Os atom, ctfa (abbv. of CO and tfa), and acac ligand for 1 and 2, acac ligand and X substituent for 3 and 4, while the lowest unoccupied molecular orbitals were mainly composed of acac ligand and X substituent. Under the time-dependent density functional theory (TDDFT) level with the polarized continuum model (PCM), the absorption and phosphorescence in CH2Cl2 media were calculated based on the optimized ground- and excited-state geometries, respectively. The calculated results show that the lowest energy absorptions at 317 (1), 342 (2), 377 (3), and 420 nm (4) are attributed to a change of ππ*/MLCT mixing transition to pure ππ* transition for 1–4, while their phosphorescence emission have similar transition properties. This indicates that the absorption and emission transition characters could be altered by adjusting the π electron-donating ability. 相似文献
992.
Zhengwei Mao Dr. Jinshan Guo Shuo Bai Tich‐Lam Nguyen Dr. Haibing Xia Dr. Yubin Huang Prof. Paul Mulvaney Prof. Dayang Wang Dr. 《Angewandte Chemie (International ed. in English)》2009,48(27):4953-4956
In the swim : Colloidal nanoparticles coated with polylactide (PLA, red) and poly(ethylene glycol) brushes (PEG, black) can transfer from organic to aqueous phases across liquid/liquid or liquid/gel interfaces during degradation of the PLA coating (see picture: first step), which is driven selectively by the hydrogen bonding of the PEG coating with the aqueous phase (second step).
993.
Jianhua Xie Weiling Kong Xiaocheng Wang Wenju Bai Lixin Wang Qilin Zhou 《Frontiers of Chemistry in China》2009,4(3):299-306
The asymmetric hydrogenation of the conformationally flexible racemic α-substituted acyclic dialkyl ketones via dynamic kinetic
resolution (DKR) has been developed by using Ru-SDPs/diamine catalysts. Chiral alcohols were produced in high yields with
good to excellent enantioselectivities (85%–97% ee) and diastereoselectivities (up to 97:3). This hydrogenation reaction provided
a new approach to the synthesis of the key intermediate of J-104118. 相似文献
994.
995.
He-Xiang Bai Jing-Mei Wang Shi-Jing Xia Quan-Rui Wang 《Journal of chemical crystallography》2011,41(3):316-321
Abstract
A novel pentaheterocyclic ring system derived from (5α)-cholestan-3-one, i.e. [1R-[1α(R*),3aβ,3bα,5aβ,12aα,12bβ,14aα]]-1-(1,5-dimethylhexyl)-1,2,3,3a,3b,4,5,11,12,12a,12b,13,14,14a-tetradecahydro-8,12a,14a-trimethyl-9-(2,4,6-trichlorophenyl)-cyclopenta[5,6]naphtho[2,1-d][1,2,4]triazolo[1,5-a]azepinium hexachloroantimonate (6) has been synthesized via the reverse-electron-demand 1,3-dipolar cycloaddition of the 1-aza-2-azoniaallene cation 4 to the triple bond of acetonitrile followed by ring enlargement. The structure of 6 was determined by NMR, IR and high-resolution mass spectra, and unequivocally confirmed by X-ray crystallographic analysis. The title compound crystallizes in monoclinic class under the space group P2-1 with a = 8.163(3) ?, b = 11.214(4) ?, c = 24.191(9) ?, α = 90°, β = 97.740(5)°, and γ = 90°. The five-membered triazole ring is essentially planar and aromatic, while the seven-membered azepine ring is not planar, but adopts a chair-like conformation. 相似文献996.
Dongbin Dang Haiyan Li Guangshui Zheng Yan Bai 《Journal of chemical crystallography》2011,41(11):1612-1615
Abstract
A new Ag(I) complex Ag(HL)2(NO3) 1 has been synthesized with 3,5-diphenylpyrazole (HL) and characterized by IR spectrum, elemental analysis and X-ray crystallography. The crystallographic data for the complex 1: triclinic P[`\text1] P{\bar{\text{1}}} , a = 10.4369(17) ?, b = 10.4837(18) ?, c = 12.963(2) ?, α = 69.318(2)°, β = 86.733(3)°, γ = 88.263(2)°, V = 1324.7(4) ?3, Z = 2, Dc = 1.530 Mg m−3, F(000) = 620, μ = 0.803 mm−1, R 1 = 0.0251, wR 2 = 0.0638. Ag(I) atom is bound to two nitrogen atoms from two ligands. In solid state there are π···π interactions and C–H···π interactions between adjacent units to generate 2D supramolecular structure. The title complex shows strong luminescent emission at 389 and 467 nm in solid state at room temperature. 相似文献997.
The simplified methodology for obtaining the Lie algebra structures of nonlinear evolution equations
The technique for obtaining the prolongation structure of differential equations is simplified. This new simplified method is used to obtain the Lie algebra structure of the Burgers–KdV equation. 相似文献
998.
By using elementary symmetric functions, this paper presents an explicit representation for the Lagrangian numerical differentiation formula as well as the error estimate for local approximation. And we also point out that the numerical differentiation formula constructed by Li [J.P. Li, General explicit difference formulas for numerical differentiation, J. Comput. Appl. Math. 183 (2005) 29-52] is actually a special case of the Lagrangian numerical differentiation formula to approximate the values of the derivatives at the nodes. 相似文献
999.
Precondition plays a critical role in the numerical methods for large and sparse linear systems. It is also true for nonlinear algebraic systems. In this paper incomplete Gröbner basis (IGB) is proposed as a preconditioner of homotopy methods for polynomial systems of equations, which transforms a deficient system into a system with the same finite solutions, but smaller degree. The reduced system can thus be solved faster. Numerical results show the efficiency of the preconditioner. 相似文献
1000.